JPH0317107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor device, and particularly to a sensor device that can check for disconnections in signal lines interposed between various switches such as photo interrupters and various control devices such as central processing units (CPUs). The present invention relates to a sensor device.

Generally, a sensor such as a photo interrupter is installed on the XY table installed in IC wire bonding equipment, etc. to detect the amount of movement of the XY table. A signal line is arranged to transmit detection signals such as the amount of movement of the. Signal lines installed in this type of moving equipment are subject to considerable stress due to the movement of XY tables, etc.
Disconnection is likely to occur. Therefore, in order to perform highly reliable control, it is required to constantly check for disconnections.

FIG. 1 shows a conventional sensor device. That is, this sensor device uses a photointerrupter 2 which is an optical sensor, and this photointerrupter 2 is composed of a light emitting diode 4 and a phototransistor 6 as a switch.
The light emitting diode 4 is connected by inserting a resistor 10 on the anode side between the voltage application terminal 8 and a reference potential point, the emitter of the phototransistor 6 is connected to the reference potential point, and a fairly long signal line 12 is connected to the collector.
Input/output devices of control equipment (not shown) such as a CPU are connected via the voltage application terminal 1.
4 through a pull-up resistor 16
Vcc is applied.

In the sensor device configured in this manner, when a voltage of several volts is applied to the voltage application terminal 8, the light emitting diode 4 emits light and the phototransistor 6 is placed in a conductive state. When the phototransistor 6 is in a conductive state, the potential of the collector of the phototransistor 6, ie, the output point 18, is maintained at approximately the reference potential point.

Then, when a shield is interposed between the light emitting diode 4 and the phototransistor 6 and the light reception from the light emitting diode 4 to the phototransistor 6 is blocked, the phototransistor 6 becomes non-conductive, and at this time, the output point 18 The potential is the applied voltage Vcc
can be switched to

However, in such a sensor device, when the signal line 12 is disconnected, it is difficult to distinguish whether the sensor output at the output point 18 is a sensor output when the phototransistor 6 becomes non-conducting, or an output due to the disconnection of the signal line 12. I can't.

Further, due to the characteristics of the configuration of the photo interrupter 2, the rise time is slow and the sensitivity is low, and if the signal line 12 is long, there are disadvantages such as noise being superimposed on the signal line 12.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sensor device that can easily detect a break in a signal line interposed between a switch such as a photo interrupter and a control device such as a CPU.

That is, the sensor device of the present invention includes a switch (photo interrupter 2) that is opened and closed by operation or information detection, and a first transistor 24 that switches in response to the opening and closing of the switch.
A switching circuit 2 that sends the switching output to the signal line 12 that is pulled up at the output point.
0 and a second transistor 30 that switches depending on the presence or absence of a direct current flowing from the signal line, and a disconnection detection circuit 22 that detects a disconnection of the signal line, and the disconnection detection circuit detects a disconnection of the signal line. When this occurs, an operating current is supplied by switching the second transistor to a display element (light emitting diode 4) that displays the disconnection state of the signal line.
4).

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 2 shows an embodiment of the sensor device of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In the figure, this sensor device includes a photo interrupter 2 as a switch and a switching circuit 2 that performs a switching operation.
0 and a disconnection detection circuit 22 for detecting a disconnection state of the signal line 12.

The switching circuit 20 includes a first transistor 2
4 and resistors 26 and 28. That is,
The base of the transistor 24 is connected to the emitter of the phototransistor 6 via a resistor 26, and connected to the reference potential point (GND) via a resistor 28.
It is connected to the.

The disconnection detection circuit 22 also includes a second transistor 30, a third transistor 32, a resistor 34,
It is composed of 36, 38, 40, and 42. That is, the collector of the transistor 30 is connected to the voltage application terminal 8 via the light emitting diode 44 as a disconnection indicating element and the resistor 34, the emitter is directly connected to the reference potential point, and the base is connected to the resistor 3.
6 to the collector of the transistor 24, and further connected to the signal line 12 via a resistor 38. transistor 32
Its emitter is connected to the voltage application terminal 8, its collector is connected to the signal line 12 via a resistor 40, and its base is connected via a resistor 42 to the anode of a light emitting diode 44. That is, the transistor 24 of the switching circuit 20 and the transistor 32 of the disconnection detection circuit 22 constitute a positive feedback circuit, and the transistor 30 is inserted into the positive feedback circuit.

The operation of the above configuration will be explained. It is assumed that a predetermined voltage Vcc is applied to the voltage application terminals 8 and 14 and that the signal line 12 is not disconnected. In this case, when the light emitting diode 4 emits light and the phototransistor 6 receives this light, the phototransistor 6 becomes conductive and the transistor 24 becomes conductive. Therefore, the output point 18 is connected to the resistor 3
8. It is short-circuited to the reference potential point via the transistor 24, and the output point 18 becomes a low potential. Furthermore, at this time, the transistor 30 is in a non-conducting state, so
The light emitting diode 44 does not light up.

Here, if a shield is interposed between the light emitting diode 4 and the phototransistor 6 and the phototransistor 6 is blocked from receiving light, the phototransistor 6
is in a non-conducting state, so the transistor 24 is in a non-conducting state. In this case, the output point 18 is connected to the voltage application terminal 14 due to the non-conducting state of the transistor 24.
Voltage Vcc is applied from , and the potential shifts to high. At this time, the signal line 12 is connected to the base of the transistor 30.
Since DC current is given from transistor 3
0 becomes conductive instantly, and the light emitting diode 44
At the same time as the transistor 32 turns on, the transistor 32 becomes conductive, and the signal line 12 becomes conductive.
is driven.

Furthermore, when the signal line 12 is disconnected, the potential at the output point 18 is always at a high potential due to the voltage Vcc applied to the voltage application terminal 14. At this time, considering the case where the transistor 24 is in a non-conducting state, since no DC current is applied to the base of the transistor 30 from the signal line 12, the transistor 30 is in a non-conducting state and the light emitting diode 44 does not light up. Therefore, to determine disconnection of the signal line 12, a test shield is used for the photointerrupter 2 to intermittently block the light, and the light emitting diode 44 is switched on in response to the switching operations of the transistors 24 and 30.
Whether or not the signal line 12 is disconnected can be determined by whether or not it blinks.

According to such a configuration, a disconnection can be detected based on the presence or absence of a weak direct current flowing through the signal line 12 without adding a special signal line to determine the disconnection of the signal line 12. In particular, the determination can be made by the sensor. This can be done in the vicinity of . Also, according to such a circuit,
Since the operating current of the transistors 30 and 32 can be made extremely small, it has the advantage of low current consumption.

Further, when the transistor 24 transitions to a non-conducting state, as the transistor 30 becomes conductive, a current due to the conduction of the transistor 32 is supplied to the signal line 12, and as a result, the potential of the signal line 12 instantly rises, causing a response. Speed can be improved. In this way, the potential of the signal line 12 changes sharply due to low output impedance driving, so the response is good, and even if the signal line 12 is long, the low output impedance makes it resistant to noise.

Furthermore, in this sensor device, since the light emitting diode 44 blinks in response to the operation of the photo interrupter 2, it functions as a monitor of the photo interrupter 2, and by intermittent blocking of light, it is possible to prevent a failure of the photo interrupter 2. can also be diagnosed.

In the embodiments, a sensor (photo interrupter 2) was used as an example of a switch. However, the sensor device of the present invention can be applied to a proximity switch, a push button switch that is opened and closed by operation, and various sensors that perform a switching operation. Similar effects can be expected when the sensor is used to detect disconnection of a signal line interposed between a switch or the like and various electronic devices, and is not limited to the sensor described in the embodiment.

As explained above, according to the present invention, a disconnection of a signal line installed between a sensor such as a photo interrupter and a control device such as a CPU can be detected reliably and easily on the sensor side, thereby improving the reliability of operation. can be increased.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional sensor device, Figure 2 is a circuit diagram showing a conventional sensor device.
The figure is a circuit diagram showing an embodiment of the sensor device of the present invention. 2...Photo interrupter (switch), 12...
Signal line, 20... Switching circuit, 22... Disconnection detection circuit, 24... First transistor, 30... Second
transistor, 44...light emitting diode (display element).

Claims (1)

[Claims] 1. A signal line comprising a switch that is opened and closed by operation or information detection, and a first transistor that switches in response to the opening and closing of the switch, and whose switching output is pulled up at an output point. a switching circuit for detecting a disconnection of the signal line; a disconnection detection circuit that includes a second transistor that switches depending on the presence or absence of a direct current flowing from the signal line, and that detects a disconnection of the signal line; A sensor device comprising: a display element that is supplied with an operating current by switching the second transistor to display a disconnection state of the signal line when detecting the disconnection state of the signal line.